1. Field of the Invention
The present invention relates to an optical plate structure, and particularly to an optical plate structure for a touch panel and a touch display panel and a touch liquid crystal display device containing the same.
2. Description of the Prior Art
Touch panels have been widely used as an interface for data input in electronic products, such as personal digit assistant (PDA), mobile phone, notebook and tablet PC. The touch panel also can have all the functions of keyboard, mouse, and the like and be for handwriting input. Particularly, the functions of input and output can be integrated into a same interface (i.e. display panel, also referred to as screen) to form a touch display panel.
FIG. 1 is a schematic cross-sectional view illustrating a conventional touch liquid crystal display device. As shown in FIG. 1, a backlight unit is disposed under a liquid crystal display panel 10. The backlight unit includes a light guide plate 12 and a white LED light source 14 disposed beside the light guide plate 12. The touch mechanism is an optical touch mechanism, that is, an infrared light LED light source 16 is disposed at another side (usually a side opposite to the white light LED light source 14) of the light guide plate 12. The emitted infrared light also passes through the light guide plate 12 and reaches the display side 18 of the liquid crystal panel 10 directly or through reflection. When a user's finger 20 approaches or touches the display side 18, the infrared light is reflected to reach a complementary metal oxide semiconductor (CMOS) image sensor 22 disposed on a side of the liquid crystal display panel 10 for light detection and electric signal conversion to carry out a touch mechanism. However, since the infrared light requires passing through the liquid crystal display panel 10, the light intensity disadvantageously massively decreases. Accordingly, it is required for the infrared light LED to provide a relatively high light intensity. As a result, the system efficiency is relatively low, and the brightness of the white light will be diminished or an infrared light LED with a more brightness should be employed.
Therefore, there is still a need for a novel optical plate structure for a touch panel to improve system efficiency.